/**
 * Software License, Version 1.0
 *
 * Copyright 2003 The Trustees of Indiana University.  All rights reserved.
 *
 *
 *Redistribution and use in source and binary forms, with or without
 *modification, are permitted provided that the following conditions are met:
 *
 *1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license;
 *2) All redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the disclaimer listed in this license in
 * the documentation and/or other materials provided with the distribution;
 *3) Any documentation included with all redistributions must include the
 * following acknowledgement:
 *
 *"This product includes software developed by the Community Grids Lab. For
 * further information contact the Community Grids Lab at
 * http://communitygrids.iu.edu/."
 *
 * Alternatively, this acknowledgement may appear in the software itself, and
 * wherever such third-party acknowledgments normally appear.
 *
 *4) The name Indiana University or Community Grids Lab or NaradaBrokering,
 * shall not be used to endorse or promote products derived from this software
 * without prior written permission from Indiana University.  For written
 * permission, please contact the Advanced Research and Technology Institute
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202.
 *5) Products derived from this software may not be called NaradaBrokering,
 * nor may Indiana University or Community Grids Lab or NaradaBrokering appear
 * in their name, without prior written permission of ARTI.
 *
 *
 * Indiana University provides no reassurances that the source code provided
 * does not infringe the patent or any other intellectual property rights of
 * any other entity.  Indiana University disclaims any liability to any
 * recipient for claims brought by any other entity based on infringement of
 * intellectual property rights or otherwise.
 *
 *LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO
 *WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 *NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF
 *INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS.
 *INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS",
 *"VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.
 *LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR
 *ASSOCIATED MATERIALS, AND TO THE PERFORMANCE AND VALIDITY OF INFORMATION
 *GENERATED USING SOFTWARE.
 */
package cgl.narada.transport.udp;

import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.Socket;

import cgl.narada.transport.Link;
import cgl.narada.transport.MonitoredLink;
import cgl.narada.transport.TransportDebugFlags;
import cgl.narada.transport.TransportException;
import cgl.narada.transport.TransportHandler;

/**
 * This is a UDP implementation of the Link interface. Say we are trying to
 * establish a communication from node A to node B. To create links one needs
 * following properties to be specified.
 * 
 * <li><b>hostname</b> - The host on which node B's process is running
 * <li><b>portnum</b> - The portnum on which node B is listening to, for
 * datagram packets.
 * 
 * @author Shrideep Pallickara $Date$ $Revision$
 */
public class UDPLink extends MonitoredLink implements Link, TransportDebugFlags {
    private String linkId;

    private Object naradaBrokeringId;

    private String linkType = "udp";

    private boolean secure = false;

    private int MAX_PACKET_SIZE = 65507;

    private String securityInformation = "Communication on this link is not encrypted";

    private boolean connectionLost = false;

    private boolean linkClosed = false;

    private String moduleName = "UDPLink: ";

    private Socket socket;

    private UDPSenderThread sender;

    private UDPLinkFactory udpLinkFactory;

    private TransportHandler transportHandler;

    public UDPLink(DatagramSocket socket, InetAddress ia, int udpPort,
        UDPLinkFactory udpLinkFactory) throws TransportException {
        this.transportHandler = udpLinkFactory.getTransportHandler();

        sender = new UDPSenderThread(socket, ia, udpPort, this);
        this.udpLinkFactory = udpLinkFactory;

        if (UDPLink_Debug) {
            System.out.println(moduleName + "Initialization complete");
        }

    }

    /** The method used to send data over a communication link */
    public void sendData(byte[] data) throws TransportException {
        if (UDPLink_Debug) {
            System.out.println(moduleName + "Sending data");
        }
        sender.sendData(data);
    }

    /**
     * The method used to send data over a communication link, this method also
     * includes information regarding the type (audio/video/xml-attachments
     * etc.) of the data encapsulated within the data stream. Using this
     * information links can optimally flush/send data across the link
     */
    public void sendData(byte[] data, String dataType)
                                                      throws TransportException {
        sender.sendData(data, dataType);
    }

    // ****************************************
    // public void sendPing()
    // throws TransportException {
    //
    // System.out.println("ping message is sending ");
    // byte [] data=new byte[9];
    // data[0] = (byte) 104;
    // String close_="<_ping_>";
    // byte [] temp=close_.getBytes();
    // System.arraycopy(temp,0,data,1,temp.length);
    // sender.sendData(data);
    // }

    /**
     * sends a message to close a link
     * 
     * @throws TransportException
     */
    public void sendCloseMessage() throws TransportException {

        if (UDPLink_Debug) {
            System.out.println(moduleName + "Close Message being sent");
        }
        byte[] data = new byte[15];
        data[0] = (byte) 103;
        String close_ = "<_close_link_>";
        byte[] temp = close_.getBytes();
        System.arraycopy(temp, 0, data, 1, temp.length);
        sender.sendData(data);
    }

    // ****************************************
    /** Sets the Id of the communication link */
    public void setLinkId(String stringId) {
        this.linkId = stringId;
    }

    /** Retrieves the String based id of the link */
    public String getLinkId() {
        return linkId;
    }

    /** The Naradabrokering Id of the node this link interacts with */
    public void setNaradaBrokeringId(Object brokeringId) {
        naradaBrokeringId = brokeringId;
    }

    /** Returns the NaradaBrokeringId associated with this link */
    public Object getNaradaBrokeringId() {
        return naradaBrokeringId;
    }

    /** Returns the type of the communication link */
    public String getLinkType() {
        return linkType;
    }

    /**
     * Sets the conditions under which communication protocols need to be
     * switched and the transport link that it should be switched to under the
     * condition. Multiple constraints can be set signifying migration to
     * different protocols.
     */
    public void setLinkMigrationConstraint(String constraint, String linkType) {
        /** NBNI */
    }

    /**
     * Check the status of the communication link at intervals specified in the
     * argument of this method
     */
    public void setLinkStatusInterval(long interval) {
        /** NBNI */
    }

    /**
     * Set the amount of time after which resources associated with this link
     * need to be garbage collected. A value of '0' indicates that this link
     * needs to be active at all times.
     */
    public void setKeepAliveTime(long keepAliveTime) {
        /** NBNI */
    }

    /**
     * Garbage collect resources associated with this link. Sockets need to be
     * closed and any resources associated with communication, needs to be
     * garbage collected
     */
    public void closeLink() {

        try {
            sendCloseMessage();
        } catch (TransportException ex) {
            System.err.println(moduleName + "Problems closing link!");
        }

        linkClosed = true;

        udpLinkFactory.reportLinkLoss(this);
    }

    /** Indicates weather communication is encrypted on this link */
    public boolean isSecure() {
        return secure;
    }

    /**
     * Information pertaining to the security strategy adopted for this
     * communication link
     */
    public String getSecurityInformation() {
        return securityInformation;
    }

    /**
     * If the senderNotification is false, it implies that the detection of
     * connection loss has been reported by the receiver thread. Proceed to
     * garbage collect the sender thread. If the boolean variable is true, it
     * implies that the receiver thread has to be garbage collected.
     */
    public void processLossOfSocketConnection(boolean senderNotification) {
        if (linkClosed) {
            /** No need to do further processing */
            return;
        }

        if (connectionLost) {
            /**
             * The loss was connection has been detected earlier, and the
             * associated garbage collection operations are being performed
             */
            return;
        }

        connectionLost = true;
        udpLinkFactory.reportLinkLoss(this);

        System.out.println(moduleName
            + "Processing of communication loss on link [" + linkId
            + " complete");
    }

    public TransportHandler getTransportHandler() {
        return transportHandler;
    }

}
